1. Field of the Invention
The present invention relates to a construction machine in which a handrail is attached to an upper rotating body such as a small-sized hydraulic excavator.
2. Description of the Related Art
A description will be given to the related art taking a small-sized hydraulic excavator (referred to as a mini excavator) serving as a preferred example of the present invention as an example.
The above excavator is provided with an upper rotating body 2 disposed on a crawler type lower traveling body 1 rotatably around a vertical axis, and a working attachment 3 installed in a front end part of the above upper rotating body 2 as shown in FIG. 7.
The working attachment 3 is provided with a raising and lowering boom 4. An arm 5 is attached to a front end of the above boom 4, and a bucket 6 is attached to a front end of the above arm 5. The reference numeral 7 denotes a boom raising and lowering cylinder for raising and lowering the boom 4, the reference numeral 8 denotes an arm cylinder for actuating the arm 5, and the reference numeral 9 denotes a bucket cylinder for actuating the bucket 6.
An operator's seat 11, an engine and other devices (not shown) and an operation device (two kinds of operation levers 12 and 13 are shown as an example) are provided taking an upper frame 10 of the upper rotating body 2 as a base.
A handrail 14 is attached over the substantially entire width before the operator's seat 11 in the upper rotating body 2. The working attachment 3 is installed immediately before the above handrail 14.
As shown in FIG. 8, the handrail 14 is formed by left and right side supports 15, 15 and a lateral railing 16 for supporting a body of an operator when the operator leans forward so as to confirm an excavating part or gets on or off the machine.
FIG. 8 shows a case where the handrail 14 is attached to a metal-sheet frame, that is an upper frame 10A formed by welding and connecting a plurality of metal plate materials.
In the case of the metal-sheet upper frame 10A, a floor plate 18 is attached astride side decks 17, 17 attached on the left and right sides. Further, lower end parts of the side supports 15, 15 of the handrail 14 are fixed to an upper surface of the above floor plate 18 with bolts.
A configuration of the metal-sheet upper frame is shown in Japanese Patent Laid-Open No. 2001-107388, and a structure for attaching the handrail to the upper frame is shown in Japanese Patent Laid-Open No. 2001-107396.
Meanwhile, in the case of a cast frame, that is an upper frame entirely cast as an integrated body, high columnar bosses 19 are conventionally provided on the left and right sides (one side is shown in the figure) of a bottom portion of an upper frame 10B as shown in FIG. 9. The floor plate 18 is attached to upper ends of the above bosses 19, and the supports 15 of the handrail are fixed to the above floor plate 18 with bolts. The reference numeral 20 denotes a bolt for attaching the floor plate 18 to the boss 19, the reference numeral 21 denotes a bolt for attaching the support 15 of the handrail to the floor plate 18, and the reference numeral 22 denotes a nut for attaching the support 15 of the handrail to the floor plate 18.
It should be noted that in the above case, the side decks 17 do not function as a member for attaching the floor plate 18.
Such a configuration of the cast upper frame is shown in Japanese Patent Laid-Open No. 2003-20683.
However, conventionally, in any case of the metal-sheet and cast upper frames 10A and 10B, only the lower ends of the side supports 15, 15 of the handrail 14 are attached to and supported by the floor plate 18. Therefore, there is a limitation on improvement in attachment strength of the handrail 14.
In the case of the cast upper frame 10B shown in FIG. 9, the high bosses 19 have to be provided in a bottom surface of the frame. Therefore, there is a problem that casting cost is increased.